Space Exploration Conspiracy Theories and the Evidence Behind Them

Key Takeaways

• Space claims require physical evidence, repeatable records, and traceable mission data.
• Apollo, Mars, ISS, UAP, and Planet X claims differ in origin and evidence quality.
• Public mistrust, image misreading, and weak data help space conspiracies persist.

Space Exploration Conspiracy Theories and the Evidence Standard

Space exploration conspiracy theories usually begin with a real event, a real institution, or a real gap in public knowledge. The subject matter is unusually attractive for rumor because spaceflight depends on remote machines, specialized instruments, government agencies, classified defense programs, complex images, and missions that most people cannot inspect in person. A rocket launch may be visible from the ground, but a lunar landing, Mars image, space station docking, or deep-space signal requires chains of telemetry, photography, engineering records, tracking stations, and expert interpretation.

A useful review starts by separating three categories that often get blended together. The first category is verifiable space history, such as the Apollo 11 mission, Mars spacecraft imaging, or the operation of the International Space Station. These subjects have records that include hardware, mission logs, telemetry, samples, independent tracking, photographs, scientific papers, and institutional archives. The second category is unresolved or incomplete information, such as some reports of unidentified anomalous phenomena, where the correct answer may be unknown because the data are weak or incomplete. The third category is conspiracy interpretation, which claims hidden control, staged evidence, or deliberate deception even when the available record offers more ordinary explanations.

The difference matters because an unexplained claim is not the same as evidence of a hidden plot. A blurry object in a photograph, a strange terrain feature on Mars, or an incomplete government file can support further investigation. It cannot, by itself, prove a staged space program, hidden alien civilization, or secret planetary threat. Evidence must do more than raise suspicion. It must identify what happened, show how the claim can be tested, and survive comparison with better data.

The table below separates recurring claim types by the kind of evidence needed to evaluate them.

The strongest space evidence usually comes from convergence. Apollo lunar rocks, for example, matter more because they fit with photographs, mission transcripts, seismology packages, orbital tracking, engineering documentation, and independent scientific study. Satellite operations matter more because weather agencies, communications providers, military organizations, universities, amateur observers, and commercial customers depend on them every day. A single photo can be misread. A system that works repeatedly for navigation, communications, weather forecasting, and science is much harder to explain away.

Space exploration conspiracy theories also differ from ordinary skepticism. Skepticism asks for evidence, tests assumptions, accepts correction, and updates its view when stronger information appears. Conspiratorial thinking often protects the original claim by treating contradictory evidence as part of the deception. That makes the claim difficult to falsify. If photographs support a mission, the photos are called fake. If samples support a landing, the samples are called planted. If independent observers confirm a spacecraft, the observers are said to be fooled or compromised. The claim survives by moving the standard of proof rather than meeting it.

The Moon Landing Hoax Claim and the Apollo Record

The most famous space exploration conspiracy theory claims that NASA staged some or all of the Apollo Moon landings. The claim usually centers on the first landing in July 1969, when Neil Armstrong and Buzz Aldrin walked on the Moon during Apollo 11 as Michael Collins orbited above in the command module. NASA conducted six crewed lunar landings between 1969 and 1972, ending with Apollo 17. Twelve astronauts walked on the lunar surface.

Moon landing hoax claims usually focus on photographs and film. Common arguments cite the appearance of shadows, the lack of visible stars in surface photographs, the movement of the American flag, or the quality of video from the lunar surface. These claims are persuasive to some viewers because they rely on ordinary intuition about photography on Earth. The lunar surface has no atmosphere, high contrast lighting, reflective dust, unusual exposure settings, and mission cameras designed for a specific environment. A photograph that appears strange under everyday assumptions can still be consistent with lunar conditions.

The Apollo evidence record extends far beyond the images. NASA’s Johnson Space Center maintains records of lunar samples, and Apollo material has been examined by researchers for decades. NASA has stated that the Apollo missions collected 2,196 samples totaling 842 pounds, or 382 kilograms, of lunar material. These samples include rocks, regolith, core tubes, and breccias formed through impact processes on the Moon. The sample record is important because it is physical, measurable, and scientifically productive long after the missions ended.

The Lunar and Planetary Institute also documents Apollo samples and Soviet Luna sample-return material. That distinction matters because the Soviet Union had strong Cold War incentives to expose a fake U.S. lunar program if the evidence supported such a charge. Instead, the Apollo sample record became part of planetary science. It can be compared with meteorites from the Moon, remote sensing of the lunar surface, and samples returned by robotic missions.

Laser ranging equipment adds another evidence stream. Apollo 11 and later missions placed retroreflectors on the Moon. Laser pulses from Earth can reflect from these arrays, helping scientists measure the Earth-Moon distance with high precision. The Institute of Physics describes lunar laser ranging as a continuing experiment linked to Apollo surface equipment. Retroreflectors alone do not prove every photograph or every mission detail, but they do support the presence of human-placed equipment at known lunar landing sites.

The hoax theory also struggles with scale. Apollo involved contractors, engineers, mission controllers, astronauts, tracking stations, recovery crews, medical teams, public broadcasts, ships, aircraft, and international monitoring. A staged version would require a large hidden operation that stayed coherent across decades, technical archives, physical samples, spacecraft hardware, and independent scientific analysis. The more evidence a hoax theory must reinterpret, the weaker it becomes unless it can produce a better explanation for all of those records together.

Mars Civilization Claims and the Face on Mars

Mars has generated a different kind of conspiracy theory. Instead of claiming that a human mission was staged, Mars claims often argue that spacecraft images reveal ancient ruins, artificial monuments, buried cities, glass tunnels, fossils, or signs of past intelligent life. The best-known example is the Face on Mars, a mesa in the Cydonia region photographed by NASA’s Viking 1 orbiter in 1976.

The Face on Mars became culturally powerful because the original image looked humanlike under low-resolution lighting. Human perception tends to detect faces quickly, even in random patterns. This tendency, called pareidolia, helps explain why people can see familiar shapes in clouds, rock formations, or shadows. On Mars, the effect became stronger because the planet already carried decades of speculation about canals, ancient life, and lost civilizations.

Later spacecraft changed the evidence. NASA’s Mars Global Surveyor acquired a higher resolution image of the Cydonia feature in April 1998. NASA also published a highest-resolution view in 2001. The improved images showed a natural mesa rather than a carved face. The European Space Agency later used data from Mars Express and NASA imagery to present Cydonia in three dimensions, further reducing the mystery created by the earlier lighting and resolution.

Mars civilization theories often rely on the first image that appears suggestive and resist later images that provide better information. This pattern is common in space conspiracy claims. A low-resolution frame becomes the anchor. Higher-resolution data, different sun angles, or improved terrain models get treated as suspicious because they weaken the original interpretation. In ordinary science, better data replaces weaker data. In conspiracy interpretation, better data may be rejected as evidence management.

Mars remains scientifically interesting without requiring hidden civilizations. NASA’s Mars program has found ancient riverbeds, minerals formed in water, organic molecules, methane questions, and evidence that Mars once had more habitable conditions than it has now. The Mars Exploration Program investigates geology, climate history, and the possibility of past microbial life. Those are significant scientific questions, but they differ from claims that NASA has concealed monuments or nonhuman artifacts.

A careful review of Mars conspiracy theories should avoid two errors. The first is treating every unusual image as evidence of artificial construction. The second is dismissing Mars as scientifically settled because many sensational claims have failed. Mars still contains unresolved scientific questions. Those questions belong to geology, chemistry, climate science, astrobiology, and mission planning, not to unsupported claims that image archives prove hidden ruins.

UAP Claims, NASA Secrecy Narratives, and the Limits of Public Evidence

Unidentified anomalous phenomena, often shortened to UAP, occupy a complicated place in space exploration conspiracy theories. Many UAP reports concern objects seen in the atmosphere rather than spacecraft or planetary exploration. Even so, UAP claims often attach themselves to NASA, military space programs, satellite surveillance, astronaut testimony, and allegations that governments have hidden evidence of extraterrestrial craft.

NASA’s 2023 UAP Independent Study Team report did not claim that UAP are extraterrestrial spacecraft. It called for a rigorous evidence-based approach, better data acquisition, reduced stigma around reporting, and improved analysis. The report’s value lies in its distinction between unknown observations and extraordinary claims. Some observations may remain unidentified because the data are poor, not because they represent alien technology.

The U.S. Department of Defense created the All-domain Anomaly Resolution Office to address UAP across air, sea, space, and land domains. AARO’s public materials emphasize data-driven investigation and explain that many reports involve ordinary objects or phenomena such as balloons, drones, aircraft, birds, weather effects, or sensor artifacts. Its historical work has also addressed claims about hidden extraterrestrial recovery programs. The office’s public conclusions have not confirmed alien spacecraft, recovered extraterrestrial bodies, or secret reverse-engineering programs.

UAP conspiracy narratives persist partly because government secrecy exists in defense and intelligence. Classified aerospace programs, sensor limitations, military test ranges, and national security procedures are real. That reality creates a space where unsupported claims can attach themselves to secrecy. The existence of classified programs does not verify claims about alien spacecraft. It does mean that public evidence can be incomplete, which makes careful wording necessary.

NASA also operates in a public-facing scientific culture. It publishes mission pages, image archives, planetary data, research products, and technical information. That openness does not mean every government-held image or sensor record is public. It does mean that claims of total concealment must explain a large public record of missions, data releases, international partnerships, academic research, and commercial space activity. A secrecy claim becomes weaker when it requires every independent source to participate in the same deception.

The table below separates ordinary unknowns from conspiracy claims that make stronger allegations.

This distinction keeps the subject factual. Unknown means unknown. It does not mean extraterrestrial, fake, secret, or impossible. Strong claims require strong evidence because they ask readers to reject more ordinary explanations and accept a hidden chain of events.

Flat Earth Space Denial and the Satellite Record

Flat Earth claims often intersect with space exploration conspiracy theories because they deny or reinterpret much of modern spaceflight. Some versions claim satellites do not exist, astronauts fake microgravity, images of Earth are computer-generated, and launch vehicles either fail secretly or disappear from view before completing a real mission. These claims require rejection of astronomy, navigation, orbital mechanics, weather forecasting, satellite communications, Earth observation, and human spaceflight records.

The satellite record is difficult for flat Earth space denial to handle because satellites produce practical services used by governments, companies, researchers, ships, aircraft, farmers, emergency responders, broadcasters, and phone networks. Weather satellites provide regular imagery. The National Oceanic and Atmospheric Administration publishes GOES full disk images, updated on short cycles. NASA’s DSCOVR EPIC camera provides daily natural-color imagery of Earth from the Earth-Sun L1 point, far beyond low Earth orbit.

Earth observation is only one part of the evidence. Global navigation satellite systems, satellite television, satellite internet, ocean monitoring, disaster response mapping, military surveillance, and scientific missions all depend on orbital assets. Amateur satellite observers can track spacecraft. Radio operators can receive signals from some satellites. Universities build and operate small satellites. Commercial launch providers deploy payloads for customers whose business models depend on working spacecraft.

Flat Earth claims often focus on image distrust. NASA’s Blue Marble images are sometimes described as artificial because many global Earth images are composites assembled from satellite passes. A composite is not automatically fake. Weather maps, planetary mosaics, and scientific images often combine data to create a complete view. The honest question is whether the method is disclosed and whether the image matches independent observations. In Earth observation, it does.

Space station denial uses a similar approach. The International Space Station is visible from the ground under the right conditions, has hosted crews for more than two decades, and receives visiting spacecraft. NASA lists basic space station facts, including its orbital period, living space, research function, and daily sunrises and sunsets. The European Space Agency’s ISS material describes the station’s partnership structure and pressurized space. Japan, Canada, Russia, Europe, and the United States have all contributed hardware, astronauts, operations, or support.

The flat Earth version of space denial requires a broad hidden system involving space agencies, commercial satellite firms, launch companies, universities, meteorologists, telecommunications firms, navigation providers, maritime users, pilots, defense agencies, and independent observers. Such a claim becomes less plausible as the number of independent systems grows. A smaller claim can be tested. A universal denial of space infrastructure must explain too much working technology without offering a better physical model.

Planet X, Nibiru, and Doomsday Astronomy

Planet X and Nibiru claims show how a real scientific idea can become attached to an unrelated conspiracy theory. Astronomers use Planet X as a generic label for a hypothetical undiscovered planet in the outer solar system. NASA’s page on hypothetical Planet X explains that a possible distant Neptune-sized planet remains theoretical and would orbit far beyond Pluto if it exists. This proposed object is sometimes called Planet Nine in scientific discussion.

Nibiru conspiracy theories make a different claim. They describe a hidden planet, brown dwarf, or massive object that will pass near Earth, cause disaster, or has been concealed by NASA. These claims became especially prominent during 2012 doomsday narratives and have resurfaced after failed predictions. NASA’s older public education page on 2012 stated that there was no Nibiru or Planet X heading toward Earth and that a large incoming object would be visible to astronomers. It also noted that the real dwarf planet Eris is in a stable distant orbit.

The difference between Planet X science and Nibiru conspiracy is evidence. Outer solar system research begins with gravitational patterns, surveys, orbital modeling, and attempts to detect faint distant objects. Nibiru claims usually begin with prophecy, internet rumor, alleged leaked images, or misread astronomy. The scientific version does not predict a near-term collision with Earth. The conspiracy version often predicts disaster and then revises the date when nothing happens.

Large hidden-object claims face strong observational problems. A planet-sized body entering the inner solar system would affect known planetary orbits, appear in survey data, and attract the attention of professional and amateur astronomers. Modern sky surveys, infrared observations, planetary ephemerides, and amateur imaging make a nearby massive object difficult to hide. Astronomers can miss faint distant objects, but a body close enough to threaten Earth would not behave like a rumor hidden inside a search engine screenshot.

Planet X claims also show the risk of name confusion. A real scientific label can lend credibility to an unrelated claim. The same pattern appears with black holes, solar storms, magnetic pole shifts, asteroid impacts, and gamma-ray bursts. These are real scientific subjects. Their existence does not validate every doomsday scenario attached to them. Sound evaluation asks whether the claim uses the scientific term accurately, identifies a real object, provides verifiable orbital data, and matches observations from independent sources.

The table below compares scientific Planet X discussion with Nibiru-style conspiracy claims.

The repeated failure of doomsday dates is evidence in its own right. A claim that predicts a visible planetary disaster and then fails should lose credibility. Rebranding the same claim with a new date does not repair the evidence problem.

Why These Claims Persist in Public Culture

Space exploration conspiracy theories persist because they satisfy more than curiosity. They can provide a story about power, deception, hidden knowledge, and the status of official institutions. Space agencies, defense contractors, intelligence offices, and aerospace companies can appear remote from everyday life. That distance makes it easier for people to imagine that the public sees only a controlled version of reality.

Psychological research helps explain the appeal without treating belief as a simple lack of intelligence. The American Psychological Association has summarized research showing that conspiracy belief can relate to intuition, perceived threat, distrust, and personal motives. A major academic review in Current Directions in Psychological Science described epistemic, existential, and social motives. Epistemic motives concern the desire for certainty and explanation. Existential motives concern control and safety. Social motives concern identity and group belonging.

Space subjects intensify these motives because they involve enormous scales and limited direct access. No one can walk outside and inspect the far side of the Moon, a Mars mesa, an asteroid trajectory, or a classified sensor record. Most people rely on institutions and experts. If trust in those institutions is low, a technical explanation can feel less satisfying than a hidden-plot narrative, even when the technical explanation has stronger evidence.

Images carry special power. A strange shape on Mars, a bright dot near the Sun, a video artifact from a spacecraft camera, or a low-resolution UAP clip can circulate without the surrounding technical context. Once a claim becomes emotionally attached to an image, later corrections may feel like attacks on the viewer’s judgment. The image becomes proof because it looks like proof, even if the chain of evidence is weak.

Popular media also keeps older claims alive. Films, television, podcasts, internet forums, and social platforms recycle Apollo hoax claims, secret Moon base stories, hidden alien contact, ancient astronaut narratives, and doomsday planet rumors. Some productions present these claims as entertainment. Others blur entertainment with investigation. The effect is cumulative. A person may encounter the same claim in different formats and mistake repetition for confirmation.

Public institutions can reduce rumor by publishing data clearly, explaining uncertainty, and avoiding defensive language. NASA’s UAP report is an example of a more careful approach: it does not treat every report as nonsense, and it does not endorse unsupported claims. It calls for better data. That approach is useful because it gives the public a path between credulity and dismissal. A claim can be taken seriously enough to examine without being accepted as true.

How to Evaluate New Space Exploration Claims

A new space exploration conspiracy theory should be tested against a few practical questions. The first question is whether the claim identifies a specific event, object, mission, image, or document. Vague claims are hard to evaluate because they can shift when challenged. Specific claims can be compared with mission data, image archives, orbital records, official statements, and independent analysis.

The second question is whether the claim depends on a single weak source. Many space rumors begin with one image, one video, one anonymous statement, or one decontextualized document. Strong claims should not rely on a single fragile point. A real lunar mission, Mars feature, satellite, or astronomical object should leave more than one type of evidence. The evidence should fit together without requiring every contradiction to become part of a hidden plot.

The third question is whether the claim makes testable predictions. Nibiru claims predicted disaster and failed. Some Mars ruin claims predicted that higher-resolution images would reveal artificial structures, but later imaging showed natural terrain. Apollo hoax claims have had decades to produce a complete alternative explanation for samples, tracking, mission records, and retroreflectors, yet the hoax model remains weaker than the historical record.

The fourth question is whether the claim distinguishes unknown from extraordinary. Some UAP cases may remain unresolved. That does not verify alien technology. Some government programs are classified. That does not verify hidden extraterrestrial spacecraft. Some images require processing. That does not verify fabrication. Scientific caution means preserving the difference between “not yet identified” and “explained by a secret conspiracy.”

A reasonable evidence checklist can help keep the evaluation focused.

Good evaluation does not require hostility toward unusual claims. It requires proportion. A claim that rewrites space history needs more than suspicion. A claim that says a Mars image shows ruins needs better terrain data than a claim that says it shows an oddly lit hill. A claim that says NASA hides a planet threatening Earth needs orbital evidence, not date-shifting prediction. The greater the claim, the more evidence it must carry.

Summary

Space exploration conspiracy theories survive because space is distant, technical, expensive, and institutionally complex. The public often sees the final image, press release, launch broadcast, or headline rather than the engineering, telemetry, sample handling, instrument calibration, peer review, and operational routine behind it. That gap can be filled with science, or it can be filled with suspicion.

The evidence record for major space activities is far stronger than the most common conspiracy claims. Apollo has mission records, returned lunar material, surface equipment, tracking history, and decades of scientific use. Mars civilization claims weakened as higher-resolution images replaced suggestive early views. ISS denial conflicts with visible passes, partner records, visiting spacecraft, research activity, and practical orbital operations. Nibiru claims repeatedly failed their own predictions. UAP claims deserve careful data collection, but an unexplained observation does not verify hidden alien technology.

The best response to space conspiracy theories is not ridicule. It is method. Claims should be made specific, tied to evidence, tested against independent records, and compared with ordinary explanations before extraordinary conclusions are accepted. Space exploration already contains enough real mystery: ancient Martian environments, lunar history, icy ocean moons, exoplanets, solar activity, asteroid hazards, and the search for life. Those mysteries become more interesting when evidence guides the story.

Appendix: Useful Books Available on Amazon

• The Demon-Haunted World
• A Culture of Conspiracy
• The Skeptics’ Guide to the Universe
• Escaping the Rabbit Hole
• Bad Astronomy

Appendix: Top Questions Answered in This Article

Did NASA Fake the Moon Landings?

The Apollo Moon landings are supported by mission records, photographs, returned lunar samples, tracking data, and surface equipment. NASA’s Apollo missions returned 382 kilograms of lunar material, and scientists continue to study those samples. The hoax theory does not provide a stronger explanation for the full body of evidence.

Why Do Some People Think the Face on Mars Is Artificial?

The original Viking image of the Cydonia feature looked face-like because of lighting, shadows, and low resolution. Later images from Mars Global Surveyor and Mars Express showed the feature as a natural mesa. The claim is a good example of pareidolia, where people perceive familiar shapes in unrelated patterns.

Are UAP the Same as Alien Spacecraft?

UAP are observations that have not been identified with the available data. That status does not mean they are extraterrestrial spacecraft. NASA’s UAP work calls for better data, stronger analysis, and careful reporting rather than unsupported conclusions.

Does Government Secrecy Prove Space Conspiracy Claims?

Government secrecy exists in defense and intelligence programs, but secrecy alone does not prove a specific hidden claim. A claim about alien technology, staged missions, or concealed planets still needs physical evidence, documents, chain of custody, or independent verification. Unknown information should not be treated as proof of a preferred explanation.

Why Do Moon Hoax Claims Focus So Much on Photographs?

Photographs are easy to circulate and easy to misunderstand without technical context. Lunar photography involved unusual lighting, no atmosphere, reflective dust, mission camera settings, and high contrast. A strange-looking image can be consistent with the Moon when the imaging conditions are understood.

Is Planet X Real?

Planet X is a scientific label sometimes used for a hypothetical distant planet beyond Neptune. NASA describes such an object as theoretical. That idea is separate from Nibiru claims, which describe a hidden planet threatening Earth and have repeatedly failed prediction tests.

Why Do Space Conspiracy Theories Keep Returning?

They return because space topics combine mystery, institutions, secrecy concerns, and hard-to-verify imagery. Online repetition can make older claims feel current. The claims often survive by treating contrary evidence as part of the alleged cover-up.

Can Satellites Be Verified by Ordinary People?

Some satellites and the International Space Station can be observed from the ground under suitable conditions. Radio operators, amateur astronomers, universities, companies, and government agencies also track or use satellites. Satellite services create practical evidence through navigation, communications, weather forecasting, and Earth observation.

Does an Unexplained Image Prove a Cover-Up?

An unexplained image shows that more context may be needed. It does not prove a cover-up by itself. Strong evidence requires traceable data, independent confirmation, and an explanation that fits better than ordinary causes such as lighting, artifacts, terrain, aircraft, drones, or weather.

What Is the Best Way to Evaluate a New Space Conspiracy Claim?

Start with the exact claim, then look for independent evidence. Check whether the claim can be tested, whether it makes predictions, and whether ordinary explanations fit the record. A claim that cannot be corrected by any evidence is usually protected belief rather than a testable explanation.

Appendix: Glossary of Key Terms

Apollo Program

The Apollo Program was NASA’s human lunar exploration program that sent astronauts to the Moon between 1968 and 1972. It included crewed lunar orbit missions, six successful crewed lunar landings, returned samples, surface experiments, and spacecraft systems developed during the Cold War space race.

Artemis Program

The Artemis Program is NASA’s campaign to return humans to the Moon and prepare for later Mars exploration. It uses the Space Launch System, Orion spacecraft, ground systems, commercial human landing systems, spacesuits, lunar science plans, and international partnerships.

Cydonia

Cydonia is a region of Mars that became famous because a Viking 1 orbiter image showed a mesa that resembled a face. Later spacecraft images with better resolution and lighting showed the feature as natural terrain rather than artificial construction.

DSCOVR EPIC

DSCOVR EPIC is a camera system on the Deep Space Climate Observatory spacecraft. It takes daily natural-color images of Earth from the Earth-Sun L1 point, giving a broad view of the sunlit side of Earth for science and public imagery.

Flat Earth Space Denial

Flat Earth space denial is the claim that spaceflight, satellites, or images of Earth are fake because Earth is not a sphere. The claim conflicts with astronomy, orbital mechanics, satellite services, navigation systems, Earth observation, and direct spacecraft tracking.

International Space Station

The International Space Station is a crewed orbital laboratory built and operated through a partnership involving the United States, Russia, Europe, Japan, and Canada. It supports science, technology demonstrations, human spaceflight operations, and international crewed missions in low Earth orbit.

Lunar Laser Ranging

Lunar laser ranging is a method that measures the distance between Earth and the Moon by reflecting laser pulses from retroreflector arrays placed on the lunar surface. Apollo astronauts deployed several of these arrays during lunar surface missions.

Lunar Samples

Lunar samples are rocks, soil, core tubes, and other material collected from the Moon. Apollo astronauts returned hundreds of kilograms of lunar material, and robotic Soviet Luna missions returned smaller samples. Scientists use these materials to study lunar formation, impacts, volcanism, and solar system history.

Nibiru

Nibiru is the name used in a doomsday conspiracy theory claiming that a hidden planet or massive object will pass near Earth and cause disaster. The claim is separate from scientific discussions of a hypothetical distant planet beyond Neptune.

Pareidolia

Pareidolia is the tendency to perceive meaningful patterns, especially faces, in random or natural shapes. It helps explain why terrain, clouds, shadows, rocks, or low-resolution images can appear to show familiar objects that are not actually present.

Planet X

Planet X is a generic astronomical label for a hypothetical undiscovered planet. Modern scientific discussion sometimes uses the idea to describe a possible distant planet beyond Neptune, but it does not support claims about a hidden body threatening Earth.

Retroreflector

A retroreflector is an optical device that reflects light back toward its source. Apollo astronauts placed retroreflector arrays on the Moon, allowing observatories on Earth to measure the Earth-Moon distance by timing returning laser pulses.

Unidentified Anomalous Phenomena

Unidentified anomalous phenomena are observations that cannot be identified with the available data. The term does not mean extraterrestrial spacecraft. It describes a status of uncertainty that may later be resolved through better sensor data, context, and analysis.